A-Alkoxyaldimines

Further reactions of allyl organometallics with a-alkoxyaldimines 1, prepared from (S)-2-(methoxymcthoxy)propionaldehyde and (R)- and (S)-l-phenylethylamine, illuminate the difference in the influence of the nitrogen chiral auxiliary and the x-alkoxy center7. 

Yamamoto et al. ° have examined the addition of allyl organometallic reagents to a-alkoxyaldimines (40) derived from (S)-2-methoxy(methoxy)propionaldehyde and (/ )- and (S)-l-phenylethylamine (equation 10). The results are summarized in Table 10. Chelation control with allyl-AlEtaMgCl, -MgCTl and -ZnBr (entries 1-3, Table 10) and nonchelation (Cram) control with allyl-Ti(Pi O)3, -B(OMe)2 and -9-BBN (entries 4-6, Table 10) parallels that observed in the allyl metal-a-alkoxyaldimine additions (involving aldimines that lack a chiral nitrogen substituent) shown in Table 6. The chirality of the a-alkoxy... 

Table 10 Chelation and Nonchelation Control in Allyl Organometallic Additions to a-Alkoxyaldimines (40) Derived from (R)- and (S)-l-Phenylethylamine (Equation lO) ...

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